TY - JOUR
T1 - Validation of Catquest-9SF-A Visual Disability Instrument to Evaluate Patient Function after Corneal Transplantation
AU - Claesson, Margareta
AU - Armitage, W. John
AU - Byström, Berit
AU - Montan, Per
AU - Samolov, Branka
AU - Stenvi, Ulf
AU - Lundström, Mats
PY - 2017/9/1
Y1 - 2017/9/1
N2 - Purpose: Catquest-9SF is a 9-item visual disability questionnaire developed for evaluating patient-reported outcome measures after cataract surgery. The aim of this study was to use Rasch analysis to determine the responsiveness of Catquest-9SF for corneal transplant patients. Methods: Patients who underwent corneal transplantation primarily to improve vision were included. One group (n = 199) completed the Catquest-9SF questionnaire before corneal transplantation and a second independent group (n = 199) completed the questionnaire 2 years after surgery. All patients were recorded in the Swedish Cornea Registry, which provided clinical and demographic data for the study. Winsteps software v.3.91.0 (Winsteps.com, Beaverton, OR) was used to assess the fit of the Catquest-9SF data to the Rasch model. Results: Rasch analysis showed that Catquest-9SF applied to corneal transplant patients was unidimensional (infit range, 0.73-1.32; outfit range, 0.81-1.35), and therefore, measured a single underlying construct (visual disability). The Rasch model explained 68.5% of raw variance. The response categories of the 9-item questionnaire were ordered, and the category thresholds were well defined. Item difficulty matched the level of patients' ability (0.36 logit difference between the means). Precision in terms of person separation (3.09) and person reliability (0.91) was good. Differential item functioning was notable for only 1 item (satisfaction with vision), which had a differential item functioning contrast of 1.08 logit. Conclusions: Rasch analysis showed that Catquest-9SF is a valid instrument for measuring visual disability in patients who have undergone corneal transplantation primarily to improve vision.
AB - Purpose: Catquest-9SF is a 9-item visual disability questionnaire developed for evaluating patient-reported outcome measures after cataract surgery. The aim of this study was to use Rasch analysis to determine the responsiveness of Catquest-9SF for corneal transplant patients. Methods: Patients who underwent corneal transplantation primarily to improve vision were included. One group (n = 199) completed the Catquest-9SF questionnaire before corneal transplantation and a second independent group (n = 199) completed the questionnaire 2 years after surgery. All patients were recorded in the Swedish Cornea Registry, which provided clinical and demographic data for the study. Winsteps software v.3.91.0 (Winsteps.com, Beaverton, OR) was used to assess the fit of the Catquest-9SF data to the Rasch model. Results: Rasch analysis showed that Catquest-9SF applied to corneal transplant patients was unidimensional (infit range, 0.73-1.32; outfit range, 0.81-1.35), and therefore, measured a single underlying construct (visual disability). The Rasch model explained 68.5% of raw variance. The response categories of the 9-item questionnaire were ordered, and the category thresholds were well defined. Item difficulty matched the level of patients' ability (0.36 logit difference between the means). Precision in terms of person separation (3.09) and person reliability (0.91) was good. Differential item functioning was notable for only 1 item (satisfaction with vision), which had a differential item functioning contrast of 1.08 logit. Conclusions: Rasch analysis showed that Catquest-9SF is a valid instrument for measuring visual disability in patients who have undergone corneal transplantation primarily to improve vision.
KW - Catquest-9SF validation
KW - Corneal Transplantation
KW - patient-reported outcome measures
UR - http://www.scopus.com/inward/record.url?scp=85027844031&partnerID=8YFLogxK
U2 - 10.1097/ICO.0000000000001255
DO - 10.1097/ICO.0000000000001255
M3 - Article (Academic Journal)
C2 - 28777777
AN - SCOPUS:85027844031
VL - 36
SP - 1083
EP - 1088
JO - Cornea
JF - Cornea
SN - 0277-3740
IS - 9
ER -